where would Ifind the heater control ciruit on a 2004 subaru

Question

P0030-where would I find this on a subaru forrester

Answer 1

This code is for the O2 sensor heater circuit. To test you need to check for battery voltage with the key on on pin# 4 on the sensor harness connector. Then check the voltage on pin # 1 and pin 2 if there is no voltage the heater in the sensor is no good. The most common issue is a failed sensor on these.